Companies such as Volkmann and others make yarn twisting machines for twisting yarns together for use in making carpet. These machines are often called twisters. Twisters typically operate at a speed of about 75 yards per minute. Twisters are traditionally manufactured to twist two yarns together at a specified rate of twist, whatever that twist rate might be. Two strands are kept under common tension and the twisters perform the desired effect.
While traditional twisting certainly has its uses, other uses of twisters and/or twisted yarn are believed to be desirable in the marketplace.
For instance, some designers are particular about the look of finished carpet. You may have a particular shade of blue provided as a sample product but the designer may want a different shade. With dyeable yarn then the carpet can be tufted and dyed to a particular shade. However, with solution dyed yarns, another sample run and then finished product would typically need to be made for the designer to proof and then buy.
To date, no one has known to provide a striated look with solution dyed yarns other than by using raised and submerged technologies of a computer driven tufting machine. To the extent there are striated looks available in the marketplace, they are done with either piece dyed or batch dyed yarn processes. Accordingly, when someone dumps bleach or a highly stainable material on the carpet, a noticeable imperfection is provided on those carpet.
Creel patents, such as U.S. Pat. Nos. 5,531,392 and 5,613,613 have been used to provide some striated patterned carpets, however, utilizing such technology is extremely unpractical for solution dyed yarns. In order to change the look of a finished product, one would likely need to completely restring the creel which would be an extremely cumbersome practice not likely to be performed by carpet manufacturers. In fact, when the applicant owned those two patents, he never attempted to use solution dyed yarn for such a practice. All carpets produced using that technology were done using piece dyable and/or skein dyable yarn to then be dyed after the tufting of the carpet to desired patterns. Depending on the particular dyes utilized, different carpet colorations could be provided.
Additionally, although two (or more) yarns fed to a single needle, there was no effort made to intentionally vary the orientation of yarns or the rate of twist per inch over a given length, especially in an effort to provide significantly less net twist over a longer length of yarn than a gross twist over a shorter segment of that longer length (at least on average).
However, the disadvantage of dyable yarn whether it be piece dyed or it be space dyed or skein dyed, is that should the carpet be then subjected to a stain or a bleach, an imperfection is then provided in the affected area. Solution dyed yarn is much less susceptible to bleaches or stains or ultraviolet light or ozone.
Improved methods of twisting yarns together and then using twisted yarns with tufting machines needles so that multiple yarns can pass through a single needle are believed to be desirable in the carpet industry.